Versatility in surgical instruments, especially those used to conduct minimally invasive procedures is of greater importance with recent advancements in the field. Minimally invasive surgical procedures are typically conducted through small ports and are characterized as endoscopic, laparoscopic, thoracoscopic, and the like. Such procedures require, not only that the instruments be precise but that the same instrument performs multiple functions.
Additionally, as surgical techniques become more advanced, surgery is increasingly being performed through smaller exposures. Minimally invasive and robotic surgeries are increasing in numbers across surgical specialties, such as neurosurgery, orthopedic surgery, cardiac surgery, thoracic surgery, and otolaryngology. Surgery on many deep portions of the body can now be performed through micro-incisions, small tubular ports, and robotic arms resulting in better surgical results, fewer complications, less pain, quicker recovery times, and decreased rates of infection. Surgical visualization and precision are even more important in these surgeries. Consequently, a device which can be adapted to administer any number of materials or substances to a specific location of the patient's body both quickly and easily will be preferred over a collection of instruments that perform the same tasks.
It is appreciated that the instruments and their payload be compatible with the surgical field. For example, it is often critical that the temperature of the instruments used be similar to the temperature of the conditional surgical setting, whether very low as in organ transplantation or at normal body temperature or at slightly above room temperature. In order to achieve the foregoing, it is often necessary to warm either the instrument or the materials the instruments will deliver. Ideally the instrument would be designed to warm the materials being used either prior to or during administration or contact with the patient.
The present invention provides such a surgical instrument. In one embodiment the present invention finds utility in the application of bone wax during orthopedic surgery.
A principal requirement of all surgery is hemostasis. When living tissue is incised, bleeding results and without hemostasis, blood loss can result in significant and life threatening anemia which may require blood product transfusion and intravenous vasopressor medications to prevent complications such as myocardial infarction, cerebral ischemia, and cardiac arrest. Additionally, bleeding obscures the surgical field which is of primary concern when surgery is performed though minimal access ports and under microsurgical magnification. Impaired visualization from bleeding can dramatically affect the accuracy, efficiency, safety, and speed of a surgical operation. At the conclusion of the operation, hemostasis is necessary to prevent post-surgical hematoma formation that can cause neurological deficit (temporary or permanent), pain, anemia, wound breakdown, and infection; all which can require re-operation, cause significant morbidity & mortality, and lead to ballooning health care expenses.
Traditionally, hemostasis is obtained during surgery of soft tissues via a combination of electrocautery and ligature. However, bone bleeding cannot be electrocauterized nor ligated. Instead, it requires application of bone wax.
Bone is a living and highly vascular tissue. When bone is incised, bleeding can be significant. Bleeding from bone mainly originates from venous channels located in the trabecular network. In operations involving the cranium, spine, chest, or other bone structure, bone wax is typically smeared along the bleeding surface to achieve hemostasis. Commonly, the instrument used to apply the bone wax is the surgeon's index finger or a blunt surgical dissector. The wax is softened to allow for it to be rolled into a ball and applied on the tip of a surgical instrument where it is then smeared along the bleeding surface. This intercalates the wax into the trabecular surface where it provides hemostasis.
The current methods for bone wax application are crude, imprecise, and often ineffective. For example, during microsurgery of the spine, millimeter scale precision is typically required for surgical maneuvers and instruments near the spinal cord and nerve roots. There is no margin of error near the spinal cord as the patient's neurological function can be permanently compromised by accidental and uncontrolled movements around the spinal cord or brain with less force than it takes to strike a key on a keyboard. Using one's finger does not provide the accuracy and control necessary to apply wax in these delicate locations.
Finally, it is known that application of bone wax impairs osteogenesis and can contribute to increased rates of infection. While it is necessary to obtain hemostasis, improved precision in application should decrease the amount of wax necessary to achieve the same result.
Bone wax is a hemostatic agent which has been used over the past century to prevent bleeding. Today, it is mostly comprised of beeswax (72.63%), and is softened with paraffin wax (14.87%) and isopropyl palmitate (12.5%). Bone wax functions by creating a physical barrier that blocks blood flow (ETHICON Bone Wax; MSDS No. Ethicon 151B; Dec. 27, 1989).
Although bone wax is widely accepted as a means to stop bleeding in bone, it has some significant disadvantages. Since bone wax is not biodegradable, it is not reabsorbed into the body. This unnatural barrier inhibits bone regeneration and increases risk of infection (Hoffmann, B., et al. “A New Biodegradable Bone Wax Substitute with the Potential to be used as a Bone Filling Material.” Journal of Materials Chemistry. 17 (2007): 4028). As excess bone wax can be harmful to a patient's recovery, surgeons attempt to minimize its use. In fact, in procedures where bone fusion is critical, the use of bone wax is avoided altogether (Magyar, C. E., et al. “Ostene, A New Alkylene Oxide Copolymer Bone Hemostatic Material, does Not Inhibit Bone Healing.” Neurosurgery 63.4 Suppl 2 (2008): 373.) Alternatives to bone wax, such as gelatin, microfibrillar collagen, and oxidized regenerated cellulose have been developed to address these negative properties, but bone wax remains the most widely used hemostatic agent (Schonauer, C., et al. “The use of Local Gents: Bone Wax, Gelatin, Collagen, Oxidized Cellulose.” Eur Spine J. 13 (2004): S89).
The term minimally invasive surgery refers to any surgery that uses a smaller than traditional opening. These surgical procedures require very small skin and soft tissue openings, often only a few centimeters in diameter. In general, minimally invasive surgeries utilize a special retractor system that creates a port to the surgical field. Such retractor systems are typically 18-25 mm wide and 40-110 mm long, however, as the average size of an American person is growing, longer retractors are often needed.
The smaller incisions afforded by these methods have numerous benefits for the patient including smaller scars, less blood loss, shorter hospital stays, and faster recovery periods (Sasani et. al., 2010). The procedures also reduce trauma, lessen the potential for blood clots, and decrease costs associated with extended therapy (Rosenthal et. al., 1994).
Given the foregoing, there remains a critical need in the art for a specific, minimally invasive applicator device